The present invention relates generally to manual transmissions, such as common manual transmissions and automated manual transmissions, which are provided with engine clutches, and particularly to engine speed synchronizers and engine speed synchronization methods for synchronizing rotational speeds of engine-side and transmission-side engaging elements of such an engine clutch by engine speed control under condition that the engine clutch is disengaged.
Manual transmissions are shifted from one speed gear to another by disengaging an engine clutch to disconnect an engine, and then operating a shift lever so as to disengage the one speed gear and engage the other under condition that the engine clutch is disengaged, and finally engaging the engine clutch to connect the engine.
If the engine clutch is engaged after operation of the shift lever under condition that the rotational speeds of the engine-side and transmission-side engaging elements of the engine clutch are not synchronous with each other, the engagement of the engine clutch may cause a great shock. If the engine clutch is engaged when the rotational speeds of the engaging elements conform to each other by chance, it may take much time to complete the shift.
Japanese Patent Application Publication No. 2007-046674 discloses a technique of engine speed synchronization control for a manual transmission. This technique is implemented by: determining a target one of speed gears of the manual transmission with reference to operation of a shift lever; calculating a target transmission input speed for the target speed gear on a basis of the transmission gear ratio of the target speed gear and transmission output speed (vehicle speed); conforming the engine speed (or the rotational speed of an engine-side engaging element of an engine clutch) to the target transmission input speed (or the rotational speed of a transmission-side engaging element of the engine clutch) under condition that the engine clutch is disengaged for allowing the manual transmission to be shifted.